1. Field of the Invention
The present invention relates generally to binder strips used to bind a stack of sheets to form a book and, in particular, a binder strip used in a binding machine having an encoded surface which can be read by the binding machine.
2. Description of Related Art
Binder strips utilizing heat activated adhesives are commonly used to bind a stack of sheets using a desk top binding machine. A typical binder strip is disclosed in detail in U.S. Pat. No. 4,496,617, the contents of which are fully incorporated herein by reference. Referring to the drawings, FIG. 1 shows an exemplary binder strip 10, with the adhesive side exposed. The strip includes an elongated substrate (not designated), typically made of paper. A central band 14 of heat activated adhesive is disposed along the length of the substrate. When activated by heat, band 14 becomes molten and has a low viscosity so as to wet the edges of the pages to be bound. A pair of outer adhesive bands 12A and 12B are provided which are made of a heat activated adhesive which is high tack and high viscosity. The outer bands function to secure the strip to the front and back cover sheets of the bound stack.
The actual binding of a stack is usually carried out by a desk top binding machine such as described in U.S. Pat. No. 5,052,873, the contents of which are fully incorporated herein by reference. FIG. 2 is a simplified diagram of an exemplary binding machine 18. The binding machine supports the stack 20 of sheets to be bound. An operator inserts a single strip 10 into an opening 21 located in the side of the machine. A sensor detects the presence of the strip 10, causing a drive motor to be activated, which causes the strip to be drawn into the machine by of a pair of pinch rollers. Once the strip is loaded into the machine, the strip is applied to the stack 20 using both pressure and heat so as to bind the stack.
Originally, the typical binding machine 18 operated with basically one type of elongated binder strip 10, with there being narrow, medium and wide strips to accommodate thin, medium and thick stacks of sheets, respectively, to be bound. A typical binding machine includes apparatus for automatically measuring the stack 20 of sheets to be bound and then indicating to an operator, by way of a display 24, the width of binder strip to be inserted into the machine. The machine is provided with various apparatus for either preventing an operator from inserting a binder strip of incorrect width into the machine or for detecting the width of the strip and then ejecting a strip if the width is incorrect.
More recently, various new types of binder strips have been developed, or are in the process of being developed, which incorporate different binding techniques. The binding machines are ideally configurable to operate differently depending upon the type of strip being used. By way of example, some strips inherently require less time to heat the heat activated adhesive than other strip types. In those cases where less time is required, the machine could complete a binding sequence more quickly as compared to other strip types. The machine must have the information as to the type of strip being used so that the binding sequence can be appropriately modified. For other types of strips, the end of the strip first inserted into the machine is critical. If the wrong end is inserted first, a proper bind cannot be carried out.
One approach would be for the operator to communicate this information to the machine by some form of manual data entry such as a keyboard 22 (FIG. 2) or the like. However, one very important objective of most desktop binding systems is to permit anyone having a minimal amount of training to operate the binding machine. If an operator is required inspect a binder strip and to then manually input the necessary information into the machine, the operator must be well trained. In any event, it is preferable to minimize the need for such manual input since even a trained operator can make an error that may result in damaging the stack of sheets to be bound. This problem will become more acute when numerous new types of strips are developed.
In addition, binder strips sometimes include gaps in the adhesive near both ends of the strip. As shown in FIG. 1, the outer adhesive bands 12A and 12B extend to both ends of the strip, but the central adhesive band 14 does not. Thus, gaps 16A and 16B are formed in the adhesive. These gaps function to receive excess molten adhesive 14 during the binding sequence. If the gap at the distal end of the strip, the end first inserted into the machine, is not present, the excess adhesive 14 at that end will have a tendency to flow away from the strip and on to components of the binding machine.
Since both ends of the strip 10 are provided with such gaps, the operator normally need not be concerned as to which end is first inserted into the machine. However, in some instances, an operator will cut a strip to accommodate a stack having a non-standard length. By way of example, a strip that is 11 inches long could be cut to 8xc2xd inches so that the top edge of an 8xc2xd by 11 inch stack can be bound rather than the normal 11 inch edge. In that event, the cut edge of the strip will not have a gap. This is not a problem if an operator knows or remembers to insert the cut strip with the end having a gap into the machine first. However, if the operator inserts the cut end first, the machine could be contaminated with adhesive.
The present invention overcomes the above-noted shortcoming of prior art strips by providing an efficient manner of encoding strips with information, typically relating to the strip type and strip direction of travel during insertion, which can be sensed by the binding machine without intervention by the operator. The binding sequence can then be automatically optimized for the strip type. The encoding also preferably indicates which strip end was inserted first so, if incorrect, the machine can sense the error, eject the strip and display an error message instructing the operator to properly reinsert the strip. These and other advantages of the present invention will become apparent to those skilled in the art upon a reading of the following Detailed Description of the Invention together with the drawings.
An encoded binder strip which controls operation of a binding machine. The binder strip includes an elongated substrate and an adhesive matrix disposed on a surface of the substrate. A predetermined encoded pattern is formed on the surface of the matrix, with the pattern including relatively low and relatively high reflectivity regions. The encoded pattern can be sensed when the machine is loaded into the binding machine so that the machine operation is optimized for the particluar type of binder strip.